Intentionally broke fast in Ramadan but was unaware of severity of kaffarah

Assalamu alaikum, If a person deliberately breaks a fast during the month of ramadan due to having sexual relations knowing that the fast would be broken but was unaware of the severity of the penalty (kaffarah) and would not have had sexual relations had they known about kaffarah, then should that person fast for 60 days or pay kaffarah? If the person is able to fast for 60 days, do they still have the option of paying kaffarah instead?